Over the past twenty years, it has been discovered that an active and mobile ankle hinders the art of skiing, because the ankle is not designed to control the massive forces created by the long lever-arms of the skis. The problem has been solved with the high-top ski boot which has totally immobilized the foot and ankle. Recent improvements have served to eliminate the last vestiges of motion of the skier's foot. The results have been wonderful on the slopes with the skis on, but walking in these ski boots has presented very serious problems and disadvantages. The present invention is directed to an improvement in the sole construction, or adaptation for use with a sole construction, of the type of ski boots just referred to which maintains solid fixation of the foot and ankle.
The tibio-talar joints and subtalar joints, together comprising what is commonly known as the ankle joint, in man performs three functions. They allow for controlling the absorption of impact after heel-strike. They allow for the advancement and rotation of the leg without the foot having to slide, or leave the floor, and allow the body weight to rest over the most stable, strongest of the foot during rest. The functions of the ankle, the foot, the lower leg and the knee, and various particular structures within these members are discussed as they relate to the design of the subject invention. In this discussion, the following terms are used and have the definition given below:
Contact Point: The contact point, as you see here, is the point of initial contact during normal walking, used at the rear most tip of the heel.
Resting Surface: The resting surface of the boot, or the boot sole, is that portion which is in contact with the floor or ground during normal standing. (The terms floor and ground are used interchangeably throughout this specification and the claims to indicate a normal walking surface, whether indoor or out, and include walking on snow, or in any other place where walking may occur.)
Incident Angle: The incident angle referred to hereinafter is the angle the leg makes to the floor during initial contact of the foot with the floor.
Center of the Knee: The center of the knee is the center of pressure for weight-bearing in the knee. The center of the knee is approximated by finding the center of the proximal end of the tibia.
Vector Point: The vector point is the center most point of the area in which force is exerted at any instant in time against the floor, resolved into a single vector with its origin upon the floor. In order for a man to stand, this vector must pass through a weight-bearing portion of the foot. The vector point is defined as the origin, on the floor, of this vector. During walking, of course, the vector point moves from the rear or posterior end of the sole to the front or anterior end of the sole as the foot rolls from the heel, upon striking, to the toe as the weight is transferred to the other foot.
Central Line: The central line is defined as an imaginary line passing perpendicular to the floor through the medial malleolus of the user's foot.
Medial: Medial and medially refer to the inside of the foot. Thus, the medial side of the right foot of the user would be on the left side of the foot whereas the medial side of the left foot of the user would be the right side of the foot.
Lateral: The terms lateral and laterally refer to the outside of the foot.
Malleolus: The malleolus is the outcropping which is commonly referred to as the ankle.
Segment: A segment, as used here, approximates about thirty percent of the length of the foot, but is defined as the distance from the heel of the user to the central line, as defined above.
Metatarsal: Metatarsal refers to the high metatarsal bones which form the skeleton of the foot which articulate with the tarsal bones and with each other proximally and distally, articulate with the proximal end of the phalanx. The metatarsal head is the enlarged portion of the foot where the metatarsal bones articulate with the phalanges.
Reference may be made to standard texts or treatise for other definitions of body structures. See, for example, HUMAN ANATOMY AND PHYSIOLOGY, Alexandra P. Spence and Elliott B. Mason, The Benjamin/Cummings Publishing Company, Inc. 1979.
There have been numerous attempts to solve the problem of walking in ski boots. Representative of these attempts are the structures disclosed in the following United States patents.
Booty U.S. Pat. No. 4,286,397, 9/1/1981 PA1 Brugger-Stuker U.S. Pat. No. 3,971,144, 7/27/1976 PA1 D'Alessandro et al U.S. Pat. No. 4,045,890, 9/6/1977 PA1 DeFever U.S. Pat. No. 4,156,316, 5/29/1979 PA1 Frey U.S. Pat. No. 4,199,880, 4/29/1980 PA1 Groves U.S. Pat. No. 4,228,602, 10/21/1980 PA1 Kastinger U.S. Pat. No. 4,194,309, 3/25/1980 PA1 Keller U.S. Pat. No. 4,294,025, 10/13/1981 PA1 Pasich U.S. Pat. No. 4,123,854, 11/7/1978 PA1 Sartor U.S. Pat. No. 4,291,473, 9/29/1981 PA1 Sturany U.S. Pat. No. 3,740,873, 6/26/1973 PA1 Viletto U.S. Pat. No. 4,261,114, 4/14/1981 PA1 Weninger U.S. Pat. No. 4,155,179, 5/22/1979 PA1 Woolley U.S. Pat. No. 4,160,301, 7/10/1979
The above patents disclose a great variety of attachments and modifications of ski soles and ski boot constructions designed to alleviate the difficulty in walking occasioned by the design of the ski boot which, of course, is designed primarily to be comfortable during skiing and to permit the skier maximum control of the skis. The Frey patent discloses an attachment for ski boots as do the patents to Booty, Groves, Woolley, DeFever, Pasich, D'Alessandro et al, Brugger-Stuker, Keller and Sturany. The patents to Sartor, Kastinger and Weninger, each discloses ski boots which have a portion which can be moved to provide a non-flat ski sole and the patent to Viletto discloses a ski boot with a sole which has a bendable portion formed therein.
While the problem of walking in ski boots is well recognized and while many efforts have been made to solve the problem, it does not appear that a solution has been found and a boot sole designed to meet the fundamental bases of the problem. Generally, the prior art has concentrated upon providing some kind of a walker device either built into or attached to the ski boot providing a higher center than ends, permitting the skier, the user, when he is walking to rock from one end of the boot to the other. No recognition of the actual rocking mechanism of the foot and angular relationships are shown to have been considered in these designs. It is an object of this invention to provide a ski boot with a sole extension, or a sole extension which is adapted to be associated with a ski boot, which is designed to permit the skier to walk comfortably and efficiently, with minimal unnatural movement of the legs, ankles and foot.